Ever since Einstein revealed his special theory of relativity, we've known that
time travel—at least moving forward through time—is possible. Einstein
didn't pull this theory, or even the notion that time travel is possible, out
of thin air. Rather, he took the knowledge of the day, saw an inconsistency—a piece of a puzzle that didn't fit, so to speak—and thought about possible
explanations.

On the following pages you'll have to think like Einstein. You'll take a look
at the same puzzle and see the problem, and you'll have to think about the same
things Einstein had to think about to resolve the problem. Maybe you've heard
the recent reports about how physically unique Einstein's brain was. Don't
panic—you won't need a superhuman brain to grasp the concepts presented. And
when you finish, not only will you understand the special theory, you will have
reasoned it out for yourself, just as Einstein did.